Julia is often jealous of other people, and has trust-issues. Out of the Trio, Julia is the hardest to befriend due to her distrusting nature. She, like Heather, likes revenge. Julia won't ever settle for second place- in and out of the arena.
Julia, despite her personality, cares a lot about her mare, Trix.
Julia often follows Heather, but the two can sometimes get in an argument, particularly when the subject involves or is on Sasha or Brit. Even though she and heather are 'best friends', Julia doesn't seem to like Heather, as she sees Heather as her no. 1 competition, both socially and in the arena.
Julia can be seen as another version of Heather to Alison. Alison makes friends easier than Julia, which Julia doesn't seem to like, especially when it comes to Brit.
Because of Heather's reaction to Sasha, Julia hates Sasha at first. In Rival Revenge, Julia starts to thaw towards Sasha because Sasha had helped her and Alison. She also starts to be more friendly toward Sasha later on, and even shows displeasure when Sasha starts to become closer to Brit. However, this friendship is short-lived because Julia starts to become worried about Sasha becoming her rival, thus making the blog Sasha and Co.
Because of what Jasmine has done to Heather and CCA riding team, Julia hates her, arguably even more than she dislikes Brit. After Sasha gives them the evidence they need to prove their innocence in Rival Revenge, Julia and Alison get Jasmine expelled from CCA.
Much to Julia's dismay, Brit becomes close friends with Heather, Alison, and Sasha. For unknown reasons, Julia doesn't trust Brit. But this is most likely because Julia doesn't make friends easily.